1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, in particular which are useful when applied to those having a bubble chamber in the middle of a flow path member.
2. Related Art
As a representive example of a liquid ejecting head ejecting liquid droplets, an ink jet type recording head ejecting ink droplets is exemplified. The ink jet type recording head has been suggested which includes, for example, a head body (a head body configured of a head case, a flow path unit and an oscillator unit) ejecting the ink droplets from a nozzle opening and a common flow path member which is fixed to the head body and supplies the ink to each head body from an ink cartridge that is a liquid storage section in which the ink is stored.
In the ink jet type recording head, the ink inside the ink cartridge is supplied to the head body via an ink flow path of the flow path member. The flow path member has a bubble chamber in which air bubbles included in the ink are stored and a filter downstream the bubble chamber, and the air bubbles are trapped in the bubble chamber so as to suppress defects such as a decreased effective area of the filter due to the blocked filter by the air bubbles (for example, see, JP-A-2007-260948).
However, since the air bubbles in the bubble chamber gradually grow and become large, the air bubbles grown excessively are periodically removed through head cleaning.
On the other hand, the air bubbles, which grow in the bubble chamber and then the volume of which increases, are further expanded, resulting from gas expansion due to a change in the ambient temperature, a change in the saturated water vapor pressure and a change in the solubility of the air with respect to the ink. As a result, when the pressure of the ink inside the ink flow path increases and the pressure inside the ink flow path exceeds meniscus withstand-pressure of the ink in the nozzle opening, the meniscus is destroyed.
In addition, when ejecting the liquid droplets via the nozzle opening, the destruction of the meniscus described above is not a problem. The reason is because the pressure inside the liquid flow path becomes a negative pressure whenever the liquid droplets are ejected and an increase in the pressure inside the flow path is suppressed by an increase in the volume of the air bubbles inside the bubble chamber. In addition, when the volume of the air bubbles inside the bubble chamber decreases due to the decrease in the ambient temperature, since the ink is supplied from the ink cartridge, the destruction of the meniscus does not occur due to the decrease in the pressure inside the flow path. Accordingly, the change in the ambient temperature causes the destruction of the meniscus within a non-use time in a state where the ejecting is stopped.
When the meniscus is destroyed due to the cause described above, there are problems in that a recording medium is damaged by the ink leakage from the nozzle opening and good printing results cannot be obtained.
In addition, the problems are simultaneously present not only in the ink jet type recording head, but also in the liquid ejecting head ejecting a liquid other than the ink and further simultaneously present in the flow path member which is utilized except for the liquid ejecting head.